Fischer E, Callaghan P T
Institute of Fundamental Sciences-Physics, Massey University, Palmerston North, New Zealand.
Phys Rev E Stat Nonlin Soft Matter Phys. 2001 Jul;64(1 Pt 1):011501. doi: 10.1103/PhysRevE.64.011501. Epub 2001 Jun 12.
Using deuterium NMR spectroscopy in a Couette cell, we observe shear-induced nematic ordering in the concentrated wormlike-micelle system CTAB/D(2)O, and our results are qualitatively consistent with birefringence studies, and in exact quantitative agreement with the degree of order measured in neutron-diffraction measurements. The width of the nematic region depends on shear rate, as well as on the temperature proximity to the equilibrium isotropic-nematic transition. Comparison of the nematic order profiles with velocity profiles obtained under identical conditions shows quite clearly that the nematic state is not identifiable with a highly sheared, low viscosity layer, and we conclude that the process of shearing induces a nematic state of high viscosity, possibly associated with mesoscale ordering. We present a simple model in which transition from the high shear branch to the viscous nematic branch is counterbalanced by subsequent relaxation of nematic order.
在库埃特流槽中使用氘核磁共振光谱，我们观察到在浓蠕虫状胶束体系CTAB/D₂O中剪切诱导的向列相有序排列，我们的结果在定性上与双折射研究一致，并且在定量上与中子衍射测量中测得的有序度精确吻合。向列相区域的宽度取决于剪切速率，以及与平衡各向同性 - 向列相转变的温度接近程度。将相同条件下获得的向列相序分布与速度分布进行比较，很清楚地表明向列相状态不能等同于高剪切、低粘度层，并且我们得出结论，剪切过程诱导出高粘度的向列相状态，可能与中尺度有序排列有关。我们提出一个简单模型，其中从高剪切分支到粘性向列相分支的转变通过随后的向列相序弛豫得到平衡。
